The present invention is directed to methods and devices for safely creating an incision through a wall of a patient""s blood vessel. Such devices and methods are useful for performing various procedures on a patient""s vascular system and heart such as the procedures described in U.S. Pat. Nos. 5,584,803 and 5,682,906 which describe coronary arty bypass grafting (CABG) and valve procedures, respectively.
Prior to occluding the ascending aorta and maintaining circulation of oxygenated blood, an incision must be made in the ascending aorta and a cannula inserted for return of blood to the patient. However, conventional methods suffer from potentially serious drawbacks. Conventional surgical techniques use a scalpel or knife to create an incision in the front wall of the ascending aorta prior to the insertion of the cannula into the aorta. Such scalpels have the potential to injure surrounding body structures. Additionally, in closed chest procedures, it is difficult and time consuming for the surgeon to separately manipulate both the scalpel and cannula.
Accordingly, there is a need for an incision method and device which can quickly and easily create an incision within the front wall of the ascending aorta through a small incision in the chest rather than a full sternotomy.
The present invention provides an improved vascular incisor, and cannula assembly and method for allowing a user to safely create an incision and insert a cannula in a body lumen. More specifically, the present invention provides an apparatus which can create an incision in a wall of the ascending aorta and insert a cannula in a fast and convenient single step process. The present invention includes a cannula and an incisor positionable within the cannula. The incisor has a blade which is moved by an actuator such as a trigger or a plunger. As the actuator is depressed, the blade is moved from a protected, retracted position to an exposed, deployed position. The exposed blade is pushed into a front wall of the ascending aorta to create an incision. As the plunger is depressed further, the blade is automatically moved to the retracted position to prevent the blade from contacting other body structures such as the back wall of the aorta. As the incisor is pushed through the incision, the cannula can be simultaneously inserted through the incision in a single step process.
In a first aspect, the present invention provides an incisor for creating a vascular incision. In one embodiment, the incisor has a rod which is movable relative to a body. A surgical element, such as a blade, is disposed at a distal end of the rod. A plunger having at least one finger engages a proximal end of the rod. When the plunger is moved from an undepressed position to a depressed position the rod and surgical element are advanced from the retracted position to the deployed position. The finger engages a ramp so that the fingers disengages from the proximal end of the rod, and the surgical element is moves back to the retracted position. In a specific configuration the incisor has a return spring to bias the plunger to the undepressed position. As the plunger is biased back to the undepressed position, the plunger fingers pass by the proximal surface of the push rod and the resilient spring force contained in the flexed plunger fingers biases the finger radially inward into the initial position and into engagement (or near engagement) with the proximal end of the push rod. At this position, the plunger and push rod are positioned for repeat actuation of the blade.
In another embodiment, the incisor includes a housing and a movable push rod. The push rod is biased toward a retracted position. Actuation of a trigger pin over a ramp moves the push rod and a surgical element from the retracted position towards a deployed position. When the trigger pin reaches a top of the ramp, the trigger pin disengages from the push rod and allows the surgical element and the push rod to return to the retracted position. In some embodiments, the trigger pin is coupled to an actuator, such as a trigger or a plunger. The actuator is actuated in the distal direction to move the trigger pin distally over the ramp. In one configuration, the actuator is biased towards an initial position so that after the surgical element has been deployed and retracted, the actuator is biased back to the initial position and the apparatus is ready for repeat actuation. In another specific configuration, the actuator is moved along a longitudinal axis of motion which is parallel to the longitudinal axis of the push rod. In yet another specific configuration, the actuator is two pivotal handles. The handles are movable between an initial outwardly separated position and a closed position in which the handles are adjacent to the body. A user squeezes the handles to the closed position to move the surgical element to the deployed position. In most configurations, the handles are biased to the initial position, such that when the handles are released, the handles return to the initial position and the incisor is ready for repeat actuation.
In yet another embodiment, the incisor has an elongate rod with a surgical element disposed at the far end of the rod. A rod spring biases the rod and surgical element in the retracted position. A hammer is positioned in the body, typically along an axis parallel with the push rod. Actuation of an actuator engages an angled cam surface against the hammer to move the hammer to compress a hammer spring. Once the trigger and cam surface move past the hammer, the cam surface disengages from the hammer so that the hammer spring can expand and push the hammer distally against the rod to move the surgical element to the deployed position. Because the rod and surgical element are biased in the retracted position by the rod spring, the surgical element is instantaneously pulled back to the retracted position.
In another aspect, the present invention provides methods of forming an incision in a tissue structure of a patient. In one method, a plunger is depressed substantially along a longitudinal axis of the device to move a surgical element from a retracted position to a deployed position. The surgical element is moved from the deployed position to the retracted position independently of further movement of the plunger. In most embodiments, the plunger is biased back to an undepressed position such that the plunger is ready for repeat actuation.
In yet another method, the present invention provides a method for inserting a cannula into a blood vessel. The method comprises positioning a tip of a device adjacent the blood vessel. An actuator is activated to move a surgical element from a retracted position to a deployed position. The surgical element is automatically moved from the deployed position to the retracted position while simultaneously inserting the cannula into the blood vessel. In most embodiments, the plunger is automatically returned to the undepressed position so that the plunger is ready for repeat actuation.
In yet another method, the present invention provides a method of creating an incision. The method comprises placing a distal tip of a device adjacent a vessel wall. An actuator is activated to compress a spring. The spring is expanded to deploy a surgical element to create an incision in a vessel. Thereafter, the surgical element is automatically retracted.
In yet another method, the present invention provides a method for occluding an aorta. A surgical element is deployed to create an opening in the aorta. The surgical element is automatically retracted and the cannula is inserted through the opening and into the aorta. The surgical element is withdrawn from the cannula and an aortic occlusion device is positioned in at least a portion of the aorta. In some methods, the aortic occlusion device includes an inflatable balloon which is expanded to occlude the aorta.
In still another aspect, the present invention provides an assembly for creating an incision in a blood vessel. The assembly includes a cannula having a lumen. An incisor having an automatically retracting surgical element is removably receivable within the lumen of the cannula. The cannula has a body and a push rod with a surgical element. An actuator is coupled to the push rod to move the surgical element between a retracted position and a deployed position. A fixed release mechanism is positioned within the body to disengage the push rod from the actuator to allow the push rod and surgical element to be biased from the deployed position to the retracted position.
In another embodiment, the assembly includes a cannula and an incisor having a hammer type assembly for retracting the surgical element. A hammer and hammer spring are positioned within the body and adjacent the push rod. A cam surface, typically coupled to an actuator, moves to compress the hammer and hammer spring. The cam surface is moved beyond the hammer and allows the hammer spring to expand so as to push the hammer distally against a push rod. The impulse from the hammer moves the surgical element from a retracted position to a deployed position. In most assemblies, the surgical element (and rod) are biased to the retracted position, such that the surgical element is immediately biased back to the retracted position.
In another embodiment, the present invention provides an assembly for treating the ascending aorta. The assembly includes a cannula having a lumen and an incisor having an automatically retracting surgical element. The incisor is removably received in the lumen of the catheter such that a surgical element is positioned near a distal end of the cannula to create an incision in the ascending aorta. An aortic occlusion device can be inserted through the lumen of the cannula and into the incision in the ascending aorta after the incisor has been removed from the cannula.
Other aspects, features, and advantages of the present invention will become apparent upon consideration of the following detailed description and the accompanying drawings.